bertele



Feb. 14, 1956 L. J. BERTELE f 2,734,424v Q WIDE ANGLE OBJECTIVES OF SIX AIR SPACED COMPONENTS T Filed Dec. 7, 1953 y 5 Sheets-Sheet l rl rz rs r4 rs 're r7 ra r9 no r11 n2 m n4 ns ne l i 4 d10 L3 L4 L5 L6. L7 L8 L9 L10 As lci `EF AB c'v o Feb. 14, 1956 L.. .1. BERTI-:LE: 2,734,424

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Feb. 14, 1956 1 VSER1-ELE 2,734,424

WIDE ANGLE OBJECTIVES OF SIX AIR SPACED COMPONENTS Filed Dec. 7, 195s 5 Sheets-Sheet. 5

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0 WIDE' ANGLE OBJECTIVES OF' SIX AIR SPACED COMPONENTS Filed Dec. 7, 1953 v 5 Sheets-Sheer, 4

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t WIDE ANGLE: OBJECTIVES OF SIX AIR SPACED COMPONENTS Filed Dec. 7, 1953 y 5 shams-sneer. 5

L1 L2 L3 L4 B1. 1.5 1.5 L7 Lg A B C D E F WIDE ANGLE OBJECTIVES OF SIX AIR SPACED COMPONENTS Ludwig Jakob Bertele, Heerbrugg, Switzerland Application December 7, 1953, Serial No. 396,513 Claims priority, application Switzerland February 13, 1950 Claims. (Cl. 88-57) This application is a continuation-impart of my application Serial No. 209,359 tiled February 5, 1951 (now abandoned).

The invention relates to optical objectives intended mainly but not exclusively for photography and projec tion. It is directed more particularly to a wide angle objective with an aperture in the neighbourhood of f/S.

In order to simplify the description and claims the focal plane at the greater distance from the corresponding principal focal plane will be termined the object and that at the smaller distance from the corresponding principal focal plane will be referred to as the image. Thus, when used for photography, the object will be the scene photographed and the image the sensitive surface of the plate or film. When used for projection the image will be the transparency or other article being projected and the object the screen on which the enlarged reproduction is exhibited.

A known form of wide angle objective is made up of four air-spaced components, of which the two inner ones have converging action and are provided with ce'- mented surfaces, while the outer components are both meniscus-shaped diverging lenses strongly concave towards the inner components. In this objective the curvature of the inner or concave surface of the diverging lens facing towards the object is so great that this surface is utilised up to a central angle of about 180, that is a hemisphere. y

Investigations have shown that objectives of this known form no longer comply fully with the more recent requirements of surveying in regard to uniformity and quality of definition.

It is the object of the invention to provide an improved wide angle objective of large aperture by constructing it with six components in which at least the greater part of the positive power is concentrated in the two middle components, the outer components being diverging menisci concave towards the diaphragm position.

With this object in view the objective of the invention is made up of six components separated from each other by air spaces and located three on each side of the dia` phragm position, the lirst and sixth components taken in consecutive order being of diverging power and of meniscus form concave towards the diaphragm position, the second and fifth components being of meniscus form concave towards the diaphragm position, the third and fourth components each being of converging power and having their extreme surfaces remote from the diaphragm position convex and separated from each other on the axis by a distance within the range 0.1 f to 1.6 f, where f is the focal length of the complete objective, and the air spaces between the first and second components and between the fifth and sixth components having each the shape of a converging lens.

It is preferable for the convex extreme surfaces of the third and fourth components to be separated from each other on the axis by a distance within the range 0.6 f to 1.4 f. 1n such cases the air space between the third and fourth components is better made not less than 0.03 f.

Patented Feb. 14, .1956

ice

In the preferred form of construction the rst, seclenses, and when this is so, it is advantageous to havethe sum of the refractive indices for the d-line of these four lenses not greater than 6.30. Also the third and fourth components are then conveniently composed each of at least two lenses cemented together. Such measures may be used to improve the correction of chromatic aberration, astigmatism, coma or distortion.

For the purpose of correcting the spherical aberration there may be included in each of the two inner converging' components a cemented surface concave towards the diaphragm position and having its centre of curvature located between itself and the other of the said two surfaces, the refractive index of the glass on the convex side of the separation surface being higher than of that on the concave side. There is preferably in at least one of the inner converging components in addition a cemented surface having its convex side towards the diaphragm, the refractive index on the convex side of this cemented surface being smaller than that on the concave side.

Where cemented surfaces are mentioned above it is also within the scope of the invention to replace one or more of such surfaces by air layers of air spaces. In the latter case the curvatures of the glass surfaces bounding the air space may be made a little different. If an air space is so introduced into a converging component, it must be understood that from the point of view of the present description and the claims the group of lenses so divided is still regarded as a single component.

With a sequence of components as described above it is possible to achieve extensive removal of distortion. The shape of the vspherical and chromatic aberration curves, as also of the astigmatism curves, is so straightcned that only slight intermediate errors remain. l

In some cases, particularly with objectives of large focal length, the construction referred to may lead to somewhat bulky objectives. Where this is the case it is better to keep to the lower part of the range of axial lengths over the extreme surfaces of the third and fourth components.

Thereby the shape of the sagittal branch of the astigmatism curve may be improved, so that this branch even at wide angles remains in the plane of best mean definition with an image radius in the optical axis corresponding with the Petzval formula of +7 f to -7 f. To achieve a similar result for the meridional branch, it is advisable to keep the axial separation between the third and fourth components less than 0.10 f.

By making the air spaces on the axis between the second and third components and between the fourth and fifth components smaller than those between the first and second components and between the fifth and sixth components, the second and lifth components can be made to contribute more towards the correction of spherical aberration, whereby the axial length over the extreme srltlces of the third and fourth components may be kept s The invention is illustrated by nine examples shown in Figures l through 9 of the accompanying drawings in conventional form.

In each ligure the six components reckoned from the La of high refractive index and medium dispersion, a converging lens L4 of medium refractive index, and a diverging lens L5 of lower refractive index. Component D is substantially almirror image of component C except in regard to precise dimensions and optical properties, being made up of the lenses Le, L7 and La. F are two simple diverging meniscus lenses L9 and Lio convex towards the image. The distance between the outer faces f5 and n2 of the converging components C and D facing the diverging components B and E is 0.967 f and the air space between the two converging components C and D is 0.0385 f. The sum of the refractive indices for the dlne of the four diverging components A,'B, E and F isl Figure 2 shows another example in which component A and component B are again simple diverging meniscus lenses L1 and L2 convex towards the object. Component C is here made up of only two lenses, namely a thick diverging lens La of high refractive index and medium dispersion and a converging lens L4. of lower refractive index. The two lenses La and L: have a common cemented surface of which the concave side is towards the diaphragm. Component D is composed of three lenses, namely a diverging lens Ls of low refractive index, la converging lens Ls of medium refractive index, and a diverging lens L1 having the highest refractive index of the component. The cemented surface between the lenses L5 and La is convex towards the diaphragm, while the lens L7 is cemented to the lens Ls by a surface concave towards the' diaphragm. Components E and F are again two simple diverging meniscusl lenses convex towards the image.

The distance between the two convex outer surfaces f5 and r11 of the converging components C and D facing the diverging components L2 and L5 is 0.973 f, and the air space between the components C and D is 0.0389 f. The sum of the refractive indices'for the d-line of the four diverging components A, B, E and F is 6.034.

An objective differing considerably from the first two is shown in Figure 3. There the second and fth components B and E are doublets and are placed much nearer Components E and to the third and fourth components C and D than to the Y rst and sixth A and F. The inner air spaces are both 0.0182 f, while the outer ones are 0.2885 f and 0.3108 f respectively. In this example the converging components C and D are of the same kind of vglass and are at zero spacing from each other. For convenience they are therefore made as a single piece of glass with a deep annular groove g to act as the diaphragm. The components B and E are constructed as doublets for better correcting chromatic aberration. The axial length over the convex outer faces of components C and D (less L4) is 0.8128 f.

Figure 4 shows an objective having many points of resemblance with that of Figure 3. The axial air space between components B and C is 0.0182 f, which is much less than that between components A and B, viz 0.2887 f. Similarly the axial air space between components D and E at 0.0182 f is much less than'the 0.3109 f separating components E and F. The axial length over the extreme surfaces of components C and D is here 0.798 f, while the axial length of the air space between these two components is 0.0172 f.

An objective is shown in Figure 5 having more resemblance with the last two than with the first two, but having the feature not exhibited by any other example in the present specification of slightly positive power in components B and E. These components are also made as doublets for the sake of better chromatic correction. The axial length over the outer convex faces of components C and D is 0.233 f.

In Figure 6 the objective shown has single diverging meniscus lenses for the four components A, B, E and F, and the axial length over the outer convex faces of components C and D is 0.509 f.

Figure 7 shows an objective in which the components A and F are constructed as doublets. The axial length Figure 9 shows an objective similar to that of Figure 8,.-

but here the axial length over the convex outer faces of components C and-D is brought near to the lower limit specified and is 0.13 f.

The optical data of the various objectives are given in the following tables, in which the number of each example corresponds with the number of the ligure illustrating it.

Example 1 [Focal length t== mm. Relative aperture t/5] Kinds oi glass Thicknesses Lenses Radi! andtisasara- Refractive Diggerindex for bb Mme number n i-100.06 L1 di l 3.90 1. 5163 64. 0

1| =13. n 107.26 Lz v d; 2.88 1. 5163 64.0

la =37. 35 n--i- 56. 55 L3 d; E-24. 88 1. 7200 50. 3

n 25.34 L4 d; =21. 18 1. 6138 58. 6

r1 73. 16 L5 d5 n 1.93 1. 5163 52. 2

lr 3.85 n 626. 3 La da 1.93 1.5163 52.2

r|n=r+ 57. 76 L1 d1 =l27.34 1.6138 50. 8

rn= 25.85 L; da =15. 56 1. 7200 29. 3

14 =36. 20 ris'l- 50. 25 L da 2.88 1. 5001 61.6

ri4= 98. 96 i ls =13. 28 r15= 51.60 Lw d10= 3.08 1.5001 61.6

Example 2 [Focal length t=100 mm. Relative aperture f/] Kinds of glass Thicknesses C Lenses Radi! andnslpra- Refractive Dsxplerindex for Abb'e d'lme number n =+101.07 L1 d|= 3. 94 1.5163 64.0

l1=13.41 rz ==|108. 35 Lz d3= 2. 91 1. 5163 64.0

h=37. 73 n 57. 12 L1 d:=25. 13 1. 7200 50. 3

n 25.59 Li 11F-23. 57 1. 6138 58.6

i la= 3.89 n =-632. 6 L5 d5= 1.95 1. 5163 52. 2

n 58.34 Lg ds==30. 34 1. 6138 50. 8

rm- 26. 97 L1 d1=12.45 1. 7200 29. 3

h==36. 56 m'- 50. 76 Ls'. dr-I 2. 91 1. 5001 61. 6

1|=13. 41 ru= 51.65 La de= 3. 11 1. 5001 61. 6

Example 3 Example 5 [Focal length 1 100 mm. Relative aperture U5] [Focal length (-100 mm. Beltive aperture 114.5]

Kind! f glass 5 Kinds 0f glass Thiekneesee Thicknesses Lenses Radix andt 121.11m- Rem Dsiieler- Lenses Radli andtiszra- Refractive Dsiisperindex for Abba index for Age 'Hina number 'Mme number f. -+11o.a4 10 f. 48.85 Lx 111-10. 12 1. 4870. 70.0 L1 d1- 4. 86 l. 5163 64.0

rz +37. 18 n B+ 25.45

191m. 111.19.04 n +5834 rl 26.58 I.; d1-10. 12 1. 5400 59. 6 La dx= 6. 51 1. 6570 57. 1

r4 =126. 94 r1 +106 85 L. d.- a. 54 1. 5400 50.9 15 L. d.- 291 1. e055 49. 2

n +2618 fl 22.86 v

h- 1.82 l1- 2. 72 n +28. 82 n =i 36.08 L1.. i4-52. 34 1. 6176 60. 3 L4 14:10. 68 1. 5600 61.2

1|- 1.82 13B 1.94 rg 25. 56 n ==21L 95 v L. d.- 2. 5s 1. 5150 41.3 20 L. d.1o.es 1. 5500 e1. z

re =1 n 36.08 Le d4- 9.11 1. 5750 57.5 lw- 2.72

nel' 54.60 fin-- 22.86

14-31.08 de- 2.91 1.6055 38.0 r11- 36- 83 "Fl-106. 85 L1 d1- 9.21 1.5015 d1- 6. 51 1.6570 57.1

m: -113. 67 m- 26. 5B

l|19.04 m= 25. 45 Le du' 4.86 l. 5163 64.0

ful- 48.86

Example 4 Example 6 [Focal length 151100 mm. Relative aperture U5] [Focal length f- 100 mm. Relative aperture 175.5]

Kinds of glass Kinds of glass Thlckneeses Thlcknesses Lenses Rad andnsgm Refractive Egfr' Lens v Rad ndtgm' Refractive Ilflf" Index for bh index for Abb d'lm nnmber 55 e number r1 =+110. 40 n Il#Hl-110.40 L1 111-10. 13 1. 4870 70.0 L1 d1=10. 13 1. 48697 70.0

n +37. 20 rz 37.2)

lll-. 87 1=28.87 n +58.37 n 58.37 In 1-10. 13 1. 5400 d|=13. 67 1. 54000 59. 6

n =127.01 r4 26. 19 I4 d1- 3.54 1.5400 l1= 1.82

1i- 1. 82 1=20. 26 l. 61761 56. 9 r|= +2884 re= 91.15 L4 d4=23. 40 1. 6176 d= 3. 14 l. 61761 36. 4

la- 1. 72 l|= 1. 72 n n tie-25. 73 1.6176 d1= 5. 47 1.61761 36.4 n 28.92 n 78.90

I1- 1. 82 de=l20.26 1.61761 60.3 nn= 25. 57 r1o= E. 92

dell 2.53 1.5750 41.3 l= 1.82 Tl1= 111-- 25. 57

d1- 9.12 1. 5750 57. 5 In d1=11.65 1. 57500 4l. 3 r= 54. 63 r11=- 54.03

3e. ss ,Palm 3555 am f n :1-

l' d1= 9.22 1.5015 55.5 d.- 9.22 1. 50149 55.5 m= 1l3. 73 m' 113- 73 76 Example 7 Example 9 [Focal lengtht-IDU mm. Relative aperture 05.5] [Focal length t-100 mm. Relative aperture f/] Kinds of glass Kinds f glass` Thicknesses Thlcknesses Lenses Radli andtslpsara- Refractive 2112191-- Lenses Radi! andtispsara- Refractive Dlisperindex for Abb index for gg Mme number Mme number n +105.0 10 n 4631 n +230 o di- 9.0 1.5020 56.5 L. r a+ 25.17 d1= 4.84 1.5163 64.0 r 36' d,- 1.0 1.5020 66.7 1.=1s.41 t l.=2s.0 L. n s+ m75 d,= 9.60 1.6034 60.7 N 57-49 r4 34.03 L: (1x-14.0 1.5400 47.2 15 La d3= 3.88 1.6034 38.0

I4-25.86 1 18 fs=+18.22 l 194 n 28.47 n 21.32 Li r :I 1e-23.1 1. 5170 60.3 Li a+ 96 89 d4= 5.81 1.5600 61.2

r 1,- 1.7 n 1F- 1.35 L. 1i-25.4 1.6176 60.3 20 L. n x 96's 1F 5. s1 1.5600 61.2

n==2s.55 1 18 rim-21.32 1:194 r== 25.25 l r10= 18.22 L. r 53 38 dii-1z0 1.5750 41.3 L, ama d= 3.88 1.6034 38.0 :l: 38'0 1.=a0.2 L. m d1= 9. 60 1. 6034 60.7 :L 230'0 d1- 1.1 1.6433 47.8 25 ma- 26'75 1918.41 y l' d1= 7.6 1. 5481 45.0 L, ma 25'17 d= 4.54 1, 5163 64.0 f14= 77.97 rull- 46. 31

I Claim:

1. A wide angle objective made up of six componentsv separated from each other by air spaces and located three on each side of the diaphragm position, the first and sixth components taken in consecutive order being of diverging power and of meniscus form concave towards the diaphragm position, the second and fifth components being of meniscus form concave towards the diaphragm position, the third and fourth components each being of converging power and having their extreme surfaces remote 4o from the diaphragm position convex and separated from each other on the axis by a distance within the range 0.1 f to 1.6 f where f is the focal length of the complete objective, and the air spaces between the first and second components and between the fifth and sixth components having each the shape of a converging lens.

2. An objective as deiined in claim 1, in which the first, second, fifth and sixth components are all of di- Example 8 versg pogen d nn d 1 1 h1 h h nf no jectiveas e e ncaim ,inw 'cte st, [Focal length t=100 mm. Relative aperture f/4.5] second, fifth and sixth components are each simple lenses. 50 4. An objective as defined in claim 1,'in which the Kinds glass first and sixth components are doublets. Lenses Rami lalllnicerss Dis ep 5. An objective as defined in claim 1, in which the tions Iitxslzraciive Sieg, second and fifth components are doublets.

d wor Abbe `6. An objective as defined in claim l, in which the air number spaces measured on the axis between the second and third n 53 05 components and between the fourth and fifth components Ll dl: 5,03 1 5163 6 0 are substantially less than those between the rst and n 25. 45 l 19 72 second components and between the fifth and sixth corn- ,3 31.42 ponents. L7 T +110 65 d1= 6. 74 1.6570 57.1 60 7. An objective as defined in claim 1, in which the air L, da: 3.01 1 6055 49.2 space measured on the axis between those surfaces of f5 23. 67 1 2 82 the third and fourth components which are adjacent to r. 28.74 zthe diaphragm position is between 0.03 f and 0.10 f. L1 r +155 13 d4=11-06 1-5600 61.2 8. An objective as dened in claim 3, in which the 1 la: 2 01 65 third and fourth components are each composed of at La n =155 13 '15:11 06 1 5600 61 2 least two individual lenses and the sum of the refractive r, 2,8 74 Indices for the d-line of the first, second, fifth and sixth r 23 67 l1= 2.82 componentsdoes not exceed 6.30. Ls w d6= 3,01 1 5055 3&0 9. Al'l ObJCCIVe 8S defllled IIl Claim 3, in which the air L7 fu=11065 d 6 74 1 6570 57 1 70 spaces between the second and third components and bem= 31.42 1 l tween the fourth and fifth lcomponents both have the r .26 45 1F19. 72 shape of a converging lens. L, s am 5.03 1.5163 64,0 10- A Wlde angle Objective made up of six components m= 53.05 separated from each other by air spaces and'located three on each side of the diaphragm position, the first and second components taken in consecutive order being single diverging meniscus lenses concave towards the diaphragm positipn and comprising between them an air space having the shape of a converging lens, the third and fourth components each being of converging'power, comprising at least two lenses and having their extreme surfaces remote from the diaphragm convex and separated from each other on the axis by a distance within the range 0.6 f to 1.4 f, where f is the focal length of the complete objective, and the fifth and sixth components being single diverging meniscus lenses concave towards the diaphragm and comprising between them an air space having the shape of a converging lens.

11. An objective as defined in claim 10 in which the axial separation between the surfaces of the third and fourth components next to the diaphragm position is between 0.03 f and 0.10 f, and the sum of the refractive indices of the first, second, fifth and sixth components does not exceed 6.30.

12. An objective as defined in claim 10, in which at least one pair of adjacent surfaces of lenses in an inner converging component is cemented.

13. An objective as deined in claim 1 in which in at least one of the two inner converging components there is a separation surface concave towards the diaphragm position with the refractive index on the concave side less than on the convex side.

14. An objective as defined in claim 1, in which each of the two inner converging components has a separation surface between lens elements which is concave towards the diaphragm position and has its centre of cunvature located between itself and the corresponding separation surface of the other inner component, the refractive index of the lens on the concave side of each of the said separation surfaces being lower than that of the lens on the convex side,

15. An objective as dened in claim 13, vin which at leastone of the two inner converging components has in addition a separation surface between lens elements convex towards the diaphragm position, the refractive index of the lens on the convex side of the said separation surface being lower than that of the lens on the concave side.

References Cited in the le of this patent UNITED STATES PATENTS 

